JP2860060B2 - Single-sided submerged arc welding method - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

FIELD OF THE INVENTION The present invention relates to a single-sided submerged arc welding method using three or more electrodes.
Especially when the welding speed is 1.0 ~
The present invention relates to a high-efficiency single-sided submerged arc welding method performed at a high speed of 2.0 m / min.

[0002]

2. Description of the Related Art In double-sided welding, many multi-electrode welding methods of 1.0 m / min or more have been proposed, and there have been many reports of actual construction results. In ordinary multi-electrode welding of one layer on both sides, the penetration depth may be about half of the plate thickness, and high-speed welding can be performed relatively easily.

[0003] Also in single-sided submerged arc welding, a technique for performing high-speed welding by improving processing conditions has been proposed (Japanese Patent Application Laid-Open Nos. 3-238174 and 3-2688).
No. 96).

[0004]

However, it is extremely difficult to increase the welding speed in single-sided welding. In single-sided welding, since it is necessary to weld from the front side and simultaneously form the back bead, if the welding speed is high, the cooling rate of the molten pool will be high even when a large current is used, so the solidification of the molten metal will occur. There is a drawback that the speed also increases. Therefore, there is a problem that the width of the back bead is not particularly widened, the shape becomes unstable, and undercut is easily generated. This disadvantage cannot be sufficiently solved by simply improving the construction conditions as in the prior art.

The present invention has been made in view of the above problems, and solves the conventional problems of high-speed single-sided submerged arc welding. In particular, by improving the backing flux, a sound back bead can be formed even in high-speed welding. It is an object of the present invention to provide a single-sided submerged arc welding method which has made it possible to obtain the same.

[0006]

SUMMARY OF THE INVENTION A single-sided submerged arc welding method according to the present invention uses a copper plate and a flux as a backing, and uses a first electrode in a single-sided submerged arc welding method using three or more electrodes. Wire diameter of 4.
0 to 4.8 mm, the wire diameter of the second electrode following the first electrode is 4.8 to 6.4 mm, and the current of the first electrode is 1400.
１1800 A, when the current of the first electrode is I ₁ and the current of the second electrode is I ₂ , 0.4I ₁ ≦ I ₂ ≦ I ₁ and the first
-The distance between the second electrodes is set to 20 to 70 mm, and the inclination of the first electrodes is
Sweep angle of 0 to 15 °, inclination of second electrode before 0 to 15 °
Bond with advanced angle and molten flux as raw material
Bond flux to flux or molten flux
A blended flux having a bulk specific gravity of 1.25 to
Adjusted to 1.75 g / cm ³ , composition was SiO ₂ : 20 to
_{45%, MgO: 25~40%,} Al 2 O 3: 0~10
_{A, CaO: 5~15%, ZrO} 2: 0~15%, Ca
Backing with F ₂ : 3 to 15% and TiO ₂ : 0 to 10%
Spread the flux on a copper plate to a thickness of 4-6 mm.
Characterized by welding at a speed of 0 to 2.0 m / min

[0007]

The present inventors have repeated various experiments in order to solve the above-mentioned problems of the prior art, and have obtained the following findings.

In order to secure the back bead at high speed, the first
A wire having a diameter of 4.0 to 4.8 mm was used as an electrode, and a high current of 1400 to 1800 A was applied to the first electrode,
Arc concentration (high current density), spread (back bead width)
And it is necessary to secure the amount of welding. When a wire having a diameter of 4.8 to 6.4 mm is used for a second electrode following the first electrode, and the current of the first electrode is I ₁ and the current of the second electrode is I ₂ Then, a current I ₂ satisfying 0.4I ₁ ≦ I ₂ ≦ I ₁ is supplied to the second electrode to cause the second electrode to control the back bead width and the back bead shape. In order to fulfill this role, the distance between the first and second electrodes must be 2
It is good to make it 0-70mm and one pool.

However, the back bead is secured at a high speed, and
The above requirements alone are not sufficient to obtain a stable and stable back bead without defects such as undercuts. The inventors of the present invention have studied the backing flux and found that the bulk specific gravity on the copper plate was 1.25 to 1.
By spraying a backing flux of 75 g / cm ³ to a thickness of 4 to 6 mm, even at a high speed of 1.0 to 2.0 m / min, there are no defects, and the shape is stable in width and height. Good back beads were obtained. Further, when the inclination of the first electrode is a receding angle of 0 to 15 ° and the inclination of the second electrode is an advancing angle of 0 to 15 °, the back bead is more stable in width and height and smooth in shape. Is obtained.

Next, the reasons for limiting the numerical values in the above-mentioned constituent elements of the present invention will be described.

[0011] In the high-speed single-sided submerged arc welding method according to the first electrode and the wire diameter invention a method of the second electrode, while ensuring sound penetration bead by the first and second electrodes, but to obtain a deposition rate required, If the wire diameter of the first electrode is less than 4.0 mm, the current range that can be used properly is low, so that it is difficult to stably melt the back surface of the steel sheet in high-speed welding at 1.0 m / min or more. On the other hand, if the wire of the first electrode exceeds 4.8 mm, an extremely high current is required to melt the back surface of the steel sheet, and the arc spreads too much. The bead width becomes too large.

If the wire diameter of the second electrode is less than 4.8 mm, the arc concentration is too good, and the back bead height becomes excessively large and the arc spread is poor, so that a sound bead width is secured. No, and the bead width becomes unstable. On the other hand, when the wire diameter of the second electrode exceeds 6.4 mm, the concentration of the arc is deteriorated, and it is difficult to secure an appropriate back bead height, and the arc is too wide, so that the undercut easily occurs. . Therefore, the wire diameter of the second electrode needs to be 4.8 to 6.4 mm.

As described above, the first electrode in the current high-speed single-sided welding of the first electrode and the second electrode increases the arc concentration by flowing a high current, drills down to the back surface of the steel plate to form a stable keyhole, and It is important to ensure the amount of welding, etc., but at a current of less than 1400 A, an arc force for digging down to the back of the steel sheet cannot be obtained, and the amount of welding is also insufficient. On the other hand, if a current exceeding 1800 A is used, the proper use current range for the wire diameter is far exceeded, and the melting speed of the wire becomes unstable, and the drilling force due to the arc becomes too strong, and the backing flux is too strong. The arc may fly directly on the lower copper plate and damage the copper plate.

The second electrode in high-speed single-sided welding serves to control the back bead width and the back bead shape as described above. Since the arc is generated from the second electrode where it is already dug down to the back of the steel plate by the first electrode, if a high current exceeding at least the current of the first electrode is used, an excessive back bead and damage to the copper plate occur, Must be avoided. Conversely, when the current of the first electrode is I ₁ and the current of the second electrode is I ₂ , I ₂ is 0.4 I ₁
If it is less than 1, the spread of the arc is insufficient, and the penetration width melted by the first current cannot be made sufficiently stable. Therefore, an undercut easily occurs, and the bead height becomes unstable.

[0015] Even in high-speed welding with a distance between the first and second electrodes of 1.0 m / min or more, in order to ensure a sound and stable back bead, the first electrode alone is not sufficient. Need help. Although the role of each electrode is as described above, in order to fulfill this role sufficiently, the first and second electrodes must form one pool. In high-speed welding at 1.0 m / min or more, the length of the molten pool formed by the first electrode is about 50 to 70 mm. In order to stably form one pool with the first and second electrodes, 1-The distance between the second electrodes must not exceed 70 mm. On the other hand, if the distance is less than 20 mm, the distance between the electrodes becomes too short, the arc of each electrode becomes unstable due to arc interference, and the stability of the back bead cannot be secured.

In high-speed single-sided welding of the backing flux, since the first electrode forming the back bead uses a particularly high current, the characteristics of the backing flux are extremely important for the stable formation of the back bead. As a result of various studies on the properties of the backing flux, it was found that the bulk specific gravity plays an important role in the width, height, shape and stable formation of the back bead. In high-speed single-sided welding, a high current is used for the first electrode forming the back bead, so that the arc concentration is good, so that the bulk specific gravity of the backing flux is 1.
If it is less than 25 g / cm ³ , the sprayed flux is completely melted, and the flux having a low bulk specific gravity has a small volume when melted. That is, the amount of slag to be generated is small, and as a result, the height of the back bead is high, and the speed is high, so that the bead width does not increase, and even if the welding conditions are controlled, the convex shape has a poorly conformable bead shape. Become. Conversely, if it exceeds 1.75 g / cm ³ , the density of the backing flux becomes too high, and when the steel sheet is distorted, the adhesion of the backing flux deteriorates and a sufficient bead height cannot be secured. .

As a backing flux, a bond flux is generally used, but it is difficult to obtain a flux having a bulk specific gravity required for high-speed single-sided welding with a general bond flux. Therefore, it is necessary to use a bond flux using a molten flux having a large specific gravity as a raw material, or a flux having a target bulk specific gravity by, for example, blending the bond flux with the molten flux or the molten flux. The components of the flux may be conventional ones. Among them, SiO ₂ : 20-45%, MgO: 25-4
0%, Al ₂ O ₃ : 0 to 10%, CaO: 5 to 15%, Z
rO ₂ : 0 to 15%, CaF ₂ : 3 to 15%, TiO ₂ :
When a material having a composition of 0 to 10% is used, a better back bead can be obtained.

Spreading thickness of backing flux In high-speed single-sided welding, the first electrode forming the backing bead uses a particularly high current, so that it is necessary to ensure the adhesion of the backing flux and the uniformity of the bead height. The thickness of the backing flux is important. When the spray thickness is 4.0 mm, the adhesion between the back surface of the steel plate and the backing flux is not sufficient, and when the spray thickness exceeds 6.0 mm, the distance between the back surface of the steel plate and the copper layer under the backing flux is too large, Even if the welding conditions are controlled, a convex bead is formed and the height becomes unstable.

Inclination of the first and second electrodes The inclination of the first and second electrodes is a factor that affects the width, height and shape of the back bead. When the inclination of the first electrode becomes an advancing angle, the width becomes smaller. Although it spreads, it is not preferable because the height tends to be insufficient, and when the receding angle exceeds 15 °, the width tends to be narrow and the height tends to be unstable. When the inclination of the second electrode becomes a receding angle, the width becomes insufficient and the height becomes unnecessarily high. Conversely, when the advancing angle exceeds 15 °, the width is widened, but the height tends to be insufficient, so that it is preferable. Absent.

In addition, the present invention relates to a single-sided submerged arc welding method, which requires a front flux and an electrode wire in addition to a backing flux. There is no particular limitation as long as it can be obtained.

[0021]

Next, examples of the present invention will be described in comparison with comparative examples.

The steel plates shown in Table 1 below were subjected to single-sided submerged arc welding using the wires shown in Table 2 and the table fluxes shown in Table 3. Table 4 shows an example of the components of the backing flux used. Table 5 shows the contents of the welding test.
Table 6 shows the results of the welding test. However,
In the column of electrode inclination in Table 5, + indicates a receding angle and-indicates an advancing angle.

[0023]

[Table 1]

[0024]

[Table 2]

[0025]

[Table 3] However, other fields are _{CO 2, B 2 O 3,} Fe-Si, Fe-Mn or the like.

[0026]

[Table 4] Others: thermosetting binder, MnO, Na ₂ O, CO ₂ etc.

[0027]

[Table 5]

[0028]

[Table 6]

[0029]

[Table 7]

The examples (test symbols 1 to 10) satisfying all the requirements of the present invention have no defects such as undercut of the back bead, and have good bead shape, height and width, and Stable results were obtained.

On the other hand, in the test symbol 11 of the comparative example, the wire diameters of the first electrode and the second electrode, and the current of the first electrode were out of the range of the present invention, and particularly the back bead height was unstable.
In the test symbol 12 of the comparative example, the distance between the electrodes of the first and second electrodes and the bulk specific gravity of the backing flux were deviated, and the shape of the back bead became particularly unstable. Test symbol 13 satisfies the welding conditions of the present invention, but since the bulk specific gravity of the backing flux was smaller than the lower limit, the back bead amount became particularly unstable. In the test symbol 14, since the distance between the first and second electrodes and the spray thickness of the backing flux exceeded the upper limits, the height of the back bead became unstable. In Test Symbol 15, since the bulk specific gravity of the backing flux was less than the lower limit, the back beads were particularly excessive. In Test Symbol 16, the current of the second electrode exceeded the upper limit, and the bulk specific gravity of the backing flux was less than the lower limit, so that the back bead amount was large and the width was unstable. In test symbol 17, the bulk specific gravity of the backing flux exceeded the upper limit, and the back bead height was insufficient. The test symbol 18 had irregular back bead shapes because the distance between the first and second electrodes was less than the lower limit. In test symbol 19, since the current of the second electrode exceeds the upper limit and the scattered thickness of the backing flux is less than the lower limit, the adhesion of the backing flux is poor, the shape of the back bead is poor, and the bead width is unstable. Became.

[0032]

As described above, according to the present invention,
Even if single-sided submerged arc welding is performed at a high speed of 1.0 to 2.0 m / min, a sound back bead can be formed, which greatly contributes to improvement of this kind of welding technique.

Continuation of the front page (58) Field surveyed (Int.Cl. ⁶ , DB name) B23K 9/18 B23K 35/362 310 B23K 37/06

Claims (1)

(57) [Claims] (1) using a copper plate and a flux as a backing,
In the single-sided submerged arc welding method using one or more electrodes, the wire diameter of the first electrode is 4.0 to 4.0.
8 mm, the wire diameter of the second electrode following the first electrode is 4.8.
And the current of the first electrode is 1400 to 180
0A, the current of the first electrode _{I 1,} when the current of the second electrode was set to _{I 2,} and _{0.4I 1 ≦ I 2 ≦ I 1} , the inter-first-second electrodes 20 to 70 mm, the first The electrode inclination is 0 to 15
゜ Set the receding angle and the inclination of the second electrode to an advancing angle of 0 to 15 °.
And bond flux made from molten flux
Blend bond flux with heat flux or molten flux
Flux having a bulk specific gravity of 1.25 to 1.75 g
/ Cm ³ , the composition is SiO ₂ : 20-45%, M
_{gO: 25~40%, Al 2 O} 3: 0~10%, Ca
_{O: 5~15%, ZrO 2:} 0~15%, CaF 2: 3
当 て 15%, TiO ₂ : Backing flux of 0 to 10%
A scan on a copper plate was sprayed to a thickness of 4~6mm, 1.0~2.
A single-sided submerged arc welding method characterized by welding at a speed of 0 m / min.